1. Field of the Invention
This invention relates to the air bag device for protection of vehicle occupants, particularly, to an air bag pack that is attachable to seat restraint and can be fastened-on by occupant. It can be manufactured into different sizes and shapes to meet the need for all kinds of occupant's body sizes and can be modified to utilize on the child safety seat or wheel chair and other types of vehicles.
2. Description of Related Art
The efficiency of air bags to protect vehicle occupants from injury during frontal crashes is well documented and proven. According to the statistics from NHTSA (National Highway Traffic Safety Administration) of USA, the air bag protection means have saved 3,148 lives as of June 1998. However, the statistics of NHTSA also indicate 61 children and 44 adult fatalities from the shock of the expanding air bags in the same period of time. Air bag fatalities are caused by a combination of proximity to deploying air bags and the current designs of those air bags. Conventionally, most of the air bag protection means are installed at fixed places inside the auto body, intended to serve as a cushion for the driver/passenger at the front seat against crash impact. Gas inflator is used to deploy the air bag when an impact beyond a certain threshold is detected. However, the deployment of the air bag is right faced toward the occupant, therefore may possibly cause injury or even fatality to occupants esp. infants or children sitting at the front seats. Moreover, for those cars equipped with two or more air bags, unless they have installed occupant sensing systems, all of the air bags would be ignited and expanded in the event of a crash that would cause damage to the auto body where the device is installed. Consequently repair & replacement cost will be quite high.
The air bag suppliers and vehicle manufacturers are trying to develop the advanced air bags to reduce the adverse effect of the conventional air bag systems. Such as: occupant classification and proximity sensors to identify whether the occupants in the keep-out zone or not; and multistage inflators to provide more tailored responses for a variety of occupants and crash severity, etc. However, there are still drawbacks of the conventional air bag devices described as below.
(1) The major factor that causes the air bag injuries or even fatalities is the direction of the air bag deployment aiming at the occupants as target. Currently, most of the conventional air bags are installed on the steeling wheel, the dashboard or window side, which they are designed to expand toward the occupants. Once the occupants are not sitting at the proper position that keeps a good distance from the air bags or they slide into the keep-out zone during the sudden crash, they may be possibly injured by the fast expanding air bags. PA1 (2) conventional air bag devices are fixedly installed at specific places in the vehicle interior. The air bag devices are mostly tailored based on adult male size. For occupants with a smaller body size or with big belly or pregnant women, these air bags may cause harm when expanded. PA1 (3) since conventional air bag devices are typically installed at fixed places, mostly at the front seats, they can provide the cushioned protection only to those people sitting at these places where the air bag devices are installed. To those people sitting on the rear seat, there is still lack of air bag protection. PA1 (4) high repair cost will be incurred due to damage of the vehicle interior where the air bags installed, such as in the steering wheel, the dashboard, the ceiling, the window and the chair side, once the expansion of the air bag occurs. To repair a deployed air bag device, one has to replace not only a new air bag module but also the damaged auto body. And if there is no "occupant sensing system" installed, all the air bags will be expanded in the event of a crash. Consequently, the repair cost would therefore be considerably high. PA1 1. Uncomfortable: It may not be comfortable to have a long cylindrical tank laying across occupant's stomach during driving, esp. to people with big round belly and pregnant women. Plus the weight of the gas tank may arise more discomfort loading to the users. PA1 2. Limited application: the long cylindrical shape of the gas tank and the location to place the crash sensor plus the long leashed cable will confine the prevalence of Portable Air Bag. PA1 3. Uncontrollable deploying direction: Due to the round shape of the tank and the lack of any guiding device, it is difficult to assure the direction of the air bag deployment will be right ahead of the user's body. Especially, at the time during the sudden crash impact, the driver's and passenger's body that carry the round tank will be at a fast moving and highly unstable stage. The uncertain deploying direction may hurt the users. PA1 4. Cumbersome: Most of all, the major concept of the Portable Air Bag, according to its inventors, was to contain all the necessary components of the conventional fixed air bag type system in a single portable unit. That means the Portable Air Bag comprises a folded air bag, a pressurized gas container, as gas inflator, a controllable gas release valve and a control/sensor for activating the device all together as "one complete portable unit" . The control/sensor device can be either designed into one single unit that set in the portable enclosure or into two separated systems. In the latter, the control device for operating the gas release valve is enclosed in the portable unit and connected to the sensor. While the electrical sensor can be designed as one single unit or a plurality of sensors positioned within the device or at a remote form. They use a plug-in module, which contains the electrical connection and a sensor to get the power supply from the automobile through a receptacle. The plug assembly is connected to the potable enclosure through a separable connector. The portable air bag has to be leashed with a cable to get its power supply, which makes this portable air bag device cumbersome. PA1 5. Unreliable: The inventor's preferred location to place the crash sensor is on the firewall to fulfill the easy access as their objective of portability. The firewall, which is at the passenger compartment, is a non-crash zone. As auto safety researchers point out, it is generally less reactive in impacts. The passenger compartment signals is initially weak but builds up rapidly and possibly not giving the sensor sufficient time to fire. The passenger compartment sensor is particularly difficult to detect the high-speed pole crashes and the angle barrier crashes (as disclosed in "Single Point Sensing and Structural Design of Vehicles" by G. Mahon & M. Masiello, SAE paper No. 920119). Crush-zone sensors are necessary for a complete sensing system ("A Critique of Single Point Crush Sensing" by D. Breed et al., SAE paper No. 920124). Single point sensor from the passenger compartment can be difficult for certain type of events and for certain types of vehicles (Sensing Consideration and Tradeoffs for Single Point Sensing" by J. P. Kelley, SAE paper No. 932916). The location to place the sensors is critically affected by the vehicle structure thus may be varied by vehicle types. Consequently, the sensing system should be designed based on the vehicle structure and is best to be installed by the automobile manufactories to be part of the auto body as a whole. The concept of "one complete portable air bag unit" that contains the sensing system may not be feasible to meet the need of all kinds of automobiles. The premise of an air bag device to offer the protection for occupants should not be jeopardized by the feasibility of the "portability".
Many researchers are trying to overcome the adverse effects of conventional air bags. For examples: the Honda corporation of Japan comes up with an air bag device, which can be buckled around the driver or/and passenger. Another new patented design named as "Portable Air Bag" (U.S. Pat. No. 5,794,971), claims a round cylindrical shaped air bag device that can be connected to the lap belt of seat belt. This "Portable Air Bag" contains a pressurized gas cylinder installed inside the enclosure, and can be activated and released the gas to deploy the air bag during a crash. These new designs have more advantages over the conventional air bags in that they may less likely cause harm to the occupants and are easily to be replaced after deployed. Both of these new models are attached on the seat belt, which means on the occupant's side. By which the direction of the deployment will be ignited from the occupant's body toward the steeling wheel or the dashboards rather faced toward the occupant's body as the conventional air bags do. Also the applications of these models will not be limited at the front seats only. They can be installed and attached with the seat belts at the rear seats.
However there are still some drawbacks can be pointed out from these new models as followings:
The "Air Belt" from Honda still has the potential hazards of causing harm to the user's head and chest due to the installation of the "Air Belt" is right at the shoulder belt of the user which is very close to the user's head. Also, its fixed size may not be suitable and be potentially harmful to those people with small figure or to pregnant women and children. While comparing to the above disadvantages of Air Belt, the characteristics of attachable and releasable of the "Portable Air Bag" overcomes the above mentioned problems. Yet due to the round cylindrical shape and the gas tank inside, the Portable Air Bag does cause some other problems. Such as: